1. Field of the Invention
This invention relates to the field of devices for indicating relative movement between two objects and more specifically to the field of devices for indicating when a lug nut has come loose on an automobile wheel.
2. Background Discussion
Lug nuts are almost universally used to secure wheels to the axles of cars. In the most common case, each of the car axles has a plurality of threaded studs on it wherein the car tires are first mounted on wheels and each wheel then secured to the axle studs by lug nuts. Like the studs, the lug nuts are threaded and in operation, they are tightened to a flush position against each wheel.
In use, the problem can subsequently arise that one or more of the lug nuts may become loose and a wheel begin to wobble. If the loose nut is not discovered and re-tightened, the wobbling can become worse. This can then distend or distort the stud hole in the wheel to the point that the wheel is ruined. Additionally, it can cause the other lug nuts to come loose and in extreme cases, the wheel may even fall off.
Presently, it is virtually impossible to tell just by looking at the lug nuts whether one or more of them are beginning to come loose. Further, it is equally difficult to manually inspect them for looseness without a torque wrench or other tool because although the nuts may be coming loose and have moved away from their tight position, they may still feel tight at least to the touch. That is, the nuts only need to move a very small amount (e.g., 1/16 of a turn or about 0.005 inches away from the wheel) to be loose enough that it may become dangerous. With such a small amount, most if not all people cannot detect any difference either visually or by simply touching the nuts. In the extreme situation, it is usually easy to tell when a nut has come completely off but by then the damage may have already been done. For example, in cars with wheel covers, a lug nut that has come completely off can usually be heard clanking around inside the cover as the car moves. Similarly, in cars with exposed wheels such as mag wheels, it is fairly easy to tell by visual inspection when a lug nut has come completely off. However, in both cases, once the nut has come completely off, it is usually too late since severe damage has often already occurred. Consequently, to prevent such damage and the accompanying unsafe conditions, it is necessary to be able to easily and quickly detect the initial movement of even the slightest amount by the lug nut away from its tight position particularly since once the nut begins to come loose, it is only a very short time before it becomes so loose as to be dangerous.
With this in mind, the present invention was developed. With the present invention, lug nuts can be quickly and easily inspected to determine if they have become loose and moved even the smallest amount away from their tight positions. Further, in the preferred embodiment of the invention, this inspection can be done visually by simply looking at the lug nuts or manually by simply running ones fingers over the outer surfaces of the lug nuts. Additionally, once a loose condition has been detected, the lug nut can be easily and quickly re-tightened with the indicator device of the present invention also being easily and quickly re-set at the same time.